Centrifugal blood pumps have been used extensively for short term circulatory assistance and perfusion. Their utility for long term ventricular assistance is limited by thrombus formation at the shaft seal. ABIOMED proposes to develop a magnetically suspended centrifugal blood pump which will have no shaft seal, making it suitable for long term circulatory support in either an implanted or extracorporeal configuration. During Phase I the applicant established the radial and axial load capacity of the bearing. In Phase II he will complete design, fabrication, and testing of the device. The applicant proposes to utilize an attraction-type magnetic bearing with a radially passive, axially active configuration. There will be a simple fluid-flow path around a toroidal rotor which is the only moving solid element. The resulting pump can be small, lightweight, simple, and very reliable. It will not be limited to short term use by the shaft seal as are the present generation of centrifugal circulatory pumps.